I. Field of the Invention:
This invention relates generally to an improved catheter structure for performing cardiovascular angioplasty procedures, and more particularly to a catheter construction which permits a variety of medical procedures to be carried out using the same catheter once it has been routed appropriately through the vascular system.
II. Description of the Prior Art:
Coronary artery disease has been a major cause of death in this country for a number of years. Due to causes which are not totally understood, over a period of time, fatty deposits and plaque build up on the interior walls of the coronary arteries leading to ischema and the discomfort of angina pectoris. Also, the narrowed coronary arteries can become blocked by thrombotic material carried in the bloodstream and, once blocked, may result in a coronary infarct.
For a number of years, coronary bypass surgery has been the procedure used to treat coronary artery disease, especially where a drug regimen has proven unsuccessful. In carrying out this treatment, the chest is opened to expose the heart, and blocked segments of coronary arteries are bypassed, using a vein harvested from the patient's own leg. Because of the traumatic nature of the surgical procedure, a prolonged hospitalization is generally required as well as an extended recuperative period.
In a paper entitled, "Nonoperative Dilation of Coronary-Artery Stenosis--Percutaneous Transluminal Coronary Angioplasty", which was published in The New England Journal of Medicine, Vol. 301, No. 2, Pgs. 61-68 (July 12, 1979), A. Gruntzig, et al disclosed a technique for opening partially occluded coronary blood vessels by inserting a catheter into the femoral artery and routing same through the vascular system and into a coronary artery. This catheter incorporates a ballon-type expander near the distal end thereof. Once the catheter is positioned with the uninflated balloon in the area occupied by the stenotic lesion, inflation of the balloon has the effect of opening the theretofore partially occluded coronary artery and restoring its patentcy.
In the Schjeldahl et al U.S. Pat. No. 4,413,989, assigned by mesne assignment to applicants' assignee, there is described a PTCA catheter having provision for profusing fluids, including blood, from the proximal end of the catheter out its distal end so that even when the balloon is inflated during the angioplasty procedure, the cells downstream from the site of the lesion being treated will not be starved of blood. The amount of fluid perfused is governed by the pressure applied at the proximal end and the size of the distal orifice through which the fluid passes. In one arrangement shown in the aforereference U.S. Pat. No. 4,413,989, a coaxial arrangement of an outer tube and an inner tube was provided and the inner tube extended beyond the distal end of the outer tube. The distal portion of the inner tube was then enlarged and the enlargement could be brought into engagement with the distal opening in the outer tube to function as a valve by manipulating the inner tube at its proximal end. In this manner, the rate of flow of fluids out the distal end of the outer tube can be regulated.
While the device described in the aforereferenced Schjeldahl et al patent provides a practical angioplasty catheter, it lacks the versatility of the angioplasty catheter of the present invention. As will be described in considerable detail hereinbelow, the catheter of the present invention can be used in a perfusing mode in which a substantial flow of blood or blood components may be perfused distally of the treatment site. In another mode, a guide wire may be inserted through the lumen of the catheter, thus narrowing the passageway through which the perfusate may flow while facilitating the routing of the catheter into the appropriate arterial branch to be treated. By utilizing a third element, namely, an inner tube coaxially disposed within the outer tube, and by appropriately manipulating the proximal end of the inner tube, it may be made to engage the inside walls of the outer tube in a sealing arrangement whereby the inflation and deflation of the expander member is facilitated. By partially withdrawing the inner tube, the flexibility of the distal portion of the catheter can be increased which facilitates the ability of the catheter to track or follow the guide wire. Finally, the guide wire and the inner tube may be totally removed from the lumen of the outer tube and replaced with an optical fiber bundle so that stenotic lesions can be lased and the site simultaneously aspirated to remove any debris created by this process.